Topic: flex fans
in Forum: C3 Cooling and Heating Systems
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i have the orignal clutch fan set up on my corvette and its starting to get alittle tired after 24 years im looking to replace it with one of those flex fans. do they work better than the orignal clutch fan setup?
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BRADENTON, FL - USA
Joined: 8/4/2002
Posts: 669
Vette(s): 1972 convertible 350 auto trans, delux int, air, ps, pb, t/t wheel, pw, 79,000 org miles Rare one year only color
a flex fan will work just as well as a clutch fan. its just personal preference. i have used both types without any problem over the years. if you plan on using a flex fan make sure it can pull enough air as there are many variables such as fan overall size(diameter),number of blades and blade pitch. All of which will affect how much air flow the fan will pull though the radiator.
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Former Member
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BRADENTON, FL - USA
Joined: 8/4/2002
Posts: 669
Vette(s): 1972 convertible 350 auto trans, delux int, air, ps, pb, t/t wheel, pw, 79,000 org miles Rare one year only color
thanks. finialy got back home and had a chance to hit the beach again and take some new pics. Took a nice ride over the sunshine skyway bridge you see in the background yesterday. its a little cooler today only going up to 60, ALMOST put the top up. 

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Just to add a little safety info.
Check the RPM rating of the fan that you are going to buy. A few models are only rated at 4000 RPM's. Get a good one if you are going to be twisting that engine to 5000+ RPM's once in awhile.
That would really suck having a blade come apart under the hood.
Lots of expensive destruction. Sarge
Check the RPM rating of the fan that you are going to buy. A few models are only rated at 4000 RPM's. Get a good one if you are going to be twisting that engine to 5000+ RPM's once in awhile.
That would really suck having a blade come apart under the hood.
Lots of expensive destruction. Sarge

TKO500 5 spd.
Borgeson Steering Box
Born 8/1981
Sequence #3975

Click here to see more pics of my Vette on CarDomain.
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Castle Rock, CO - USA
Joined: 4/21/2002
Posts: 179
Vette(s): 1973 T-Top
1993 Coupe
Hello,
A flex fan tends to generate more noise than a clutch type fan.
Alex

A flex fan tends to generate more noise than a clutch type fan.
Alex


Fairfax, VA - USA
Joined: 8/26/2002
Posts: 38
Vette(s): 1968 Corvette Roadster, 427,12.25-1 comp ratio, 582 Hp, 4 sp., 3.36, Steeroids rack and pin. pwr strg, pwr bks, serp. pulleys, 1968 (Factory) L-88 Hood, Vette Br. suspension, Both tops, MSD ign.
Another consideration with flex fans is to be sure to space the fan properly so that it reaches into the shroud. Lots of people (me included) have put them on shy of the fan shroud (too close to the motor) and developed overheating problems as a result. The location is very important.
Yes they are noisy as well as fragile. They can get banged up easily and this knocks them off balance and there go the water pump bearings!
I spent lots of time playing with flex fans and went back to the original fan for my car with a new (stock) fan clutch and my temperatures went down.
It is hard to believe at times but those great guys in St. Louis actually knew a good thing about this aspect of cooling systems!
Good Luck!
Christopher T. McCloskey
Yes they are noisy as well as fragile. They can get banged up easily and this knocks them off balance and there go the water pump bearings!
I spent lots of time playing with flex fans and went back to the original fan for my car with a new (stock) fan clutch and my temperatures went down.
It is hard to believe at times but those great guys in St. Louis actually knew a good thing about this aspect of cooling systems!
Good Luck!
Christopher T. McCloskey

Is the stock fan supposed to enguage and disenguage?
Right now my 427 sounds like and Airplane. The fan is allways running. any thoughts? I took the fan off and the clutch does move but it seems stiff. is my clutch bad?
Right now my 427 sounds like and Airplane. The fan is allways running. any thoughts? I took the fan off and the clutch does move but it seems stiff. is my clutch bad?
Does it show signs of leaking fluid? If so it is probably shot. Yes, the fan does engage and disengage, the clutch is supposed to tighten up on the shaft when it is hot and loosen when it cools. The thermal clutch is a design that does function well but I have seen a lot of defective ones over the years. Usually the case is that the clutch doesn't tighten up like it should and you see overheating problems. In your case I'm wondering if it isn't starting to freeze up.
It is normal for the shaft to feel stiff when you turn it with your hand.

It is normal for the shaft to feel stiff when you turn it with your hand.

'69 350/350 conv.
in Forum: C3 Cooling and Heating Systems
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